The prior art discloses processes for the mechanical separation of components, in which a maximum of up to 90% of the metals of value present can be recovered. In addition to the mechanical separation, disposal of the pollutant-containing organic constituents which remain is necessary.
DE A 9420410, DE A 9320018 and DE A 3518725 C2 disclose a process for the thermal treatment of electronics scrap by pyrolysis. In this process, the pyrolysis carbon remaining in the residue is removed in a further work-up. High concentrations of dioxins and furans sometimes have to be reckoned with in this pyrolysis carbon. DE A 9420410, DE A 9320018 and DE A 3518725 C2 are concerned with a process for the thermal recycling of metallic articles which are mixed or coated with organic substances or are similarly contaminated, for example paint or oil cans or canisters, drums or other containers. These starting components, referred to as scrap, are introduced into a carbonization chamber in which they are firstly treated thermally essentially without introduction of oxygen. This carbonization chamber is operated during the carbonization phase with external heating and at a temperature in the range from about. 250 to 500° C. and has a rotating drum which is operated at a speed of rotation of from 1 to 2 revolutions per minute during the process. Combustible pyrolysis gases or combustible pyrolysis oils are formed during the carbonization phase and these can be used to bring the carbonization chamber to temperature. The carbonization process is followed by an oxidation process in which the pyrolysis gases produced during the carbonization process are burnt in the same chamber but at a later time by introduction of oxygen. This burning of the pyrolysis gases can also be carried out in an after-combustion chamber located downstream of the carbonization chamber. This text also addresses the recycling of sweepings comprising noble metal dust as can arise, inter alia, in the jewelry industry.
The carbonization/oxidation process is described in detail in a publication W L B Wasser, Luft und Boden 3/2000, on page 46 “Edelmetall-Recycling: Verschwelung statt Verbrennung”.
All these processes have the disadvantage that more than 10% of the metal from the scrap cannot be reused and they involve sequential steps.
It is therefore an object of the invention to provide a simple process by means of which a secondary raw material is obtained in high yields (>90%) from metal-containing starting materials, in particular electronics scrap.